Aircraft/spacecraft hangars (also known as “hangars”) include buildings or structures designed to maintain, store, and protect aircraft (i.e. commercial aircraft, military aircraft, planes, helicopters, etc.) and/or spacecraft (i.e. launch vehicles, crewed vehicles, robotic probes, etc.).
Hangars are structurally distinct structures known for their enormous size, massive clear-span framing, colossal doors, enhanced fire suppression systems, and heavily reinforced foundations.
Famous aircraft/spacecraft hangars include: NASA’s Kennedy Space Center (KSC) Orbiter Processing Facility (OPF); The Cape Canaveral Space Force Station Hangar C; and the Moffett Federal Airfield Hangar One in Mountain View, CA.
Aircraft hangars are generally classified based on functionality and with respect to National Fire Protection Association (NFPA) Standard on Aircraft Hangars, NFPA 409.
Key NFPA 409 Fire Protection Classifications include:
- Group I: Largest facilities; single fire area of 40,000 sqft (3,716 sq m), or more
- Group II: Medium-sized facilities; single fire area between 12,001 and 40,000 sq ft.
- Group III: Smaller facilities; single fire area of 12,000 sqft or
- Group IV: Specific membrane-covered, rigid steel frame
Key Functional & Design Aircraft Hangar Classifications include:
- T-Hangars
- Box/Community Hangars
- Maintenance, Repair, and Overhaul (MRO) Hangars
- Corporate/Fixed Base Operator (FBO) Hangars
- Military Hangars
Similarly, spacecraft hangars are classified by their operational environment (terrestrial vs. extraterrestrial), functionality, and scale.
Key Functional & Design Spacecraft Hangar Classifications include:
- Vertical Assembly/Integration Hangars: (i.e., the Vehicle Assembly Building).
- Horizontal Processing Hangars
- Mobile Service/Transport Hangars
Hangars include Reinforced Concrete structures (i.e. hardened hangars), Pre-Engineered Metal Buildings (PEMBs), and conventional steel buildings (CSBs). That said, due to their size and complexity – which includes large clear-span roofs, oversized doors, high wind exposure, fire-protection complexity, aircraft fuel hazards, corrosion exposure, crane/hoist loads, and operational impact risks – hangars have distinct design requirements.
Governing aircraft/spacecraft hangar design codes and standards include the International Building Code (IBC), the American Society of Civil Engineers (ASCE), “Minimum Design Loads and Associated Criteria for Buildings and Other Structures” (ASCE 7), the American Institute of Steel Construction (AISC) Steel Construction Manual, the American Concrete Institute (ACI) Building Code Requirements for Structural Concrete (ACI 318), the National Fire Protection Association (NFPA) Standard on Aircraft Hangars, (NFPA 70). Similarly, while aircraft hangars must also comply with Federal Aviation Administration (FAA) Advisory Circulars (AC 150/5300) and local airport authority minimum standards, spacecraft hangars must comply with the Unified Facilities Criteria (UFC) Standards UFC 4-211-01N/UFC 4-211-01 and other applicable codes.
For Construction-Defect Defense Litigators, ascertaining the causation, and thus liability of a construction defect, while avoiding technical blindsides and reining in projected costs can be a daunting process. This is most notable for litigators seeking
causation for construction and design standard-of-care violations, and those seeking causation for code violations and defective material quality.
For construction or design defects involving major components it is generally advisable to engage construction-defect experts early on in the case to determine causation, reduce risks, and limit costs.
Particularly, for construction or design defects involving
structural components it is generally advisable to engage construction-defect and structural forensic engineering experts early on in the case to determine causation, reduce risks, and limit costs.
Below are the top 5 structural blind spots in Hangar Renovation for Construction-Defect Defense Litigators.
For construction defects or design defects involving structural components it is generally advisable to engage construction-defect and structural forensic engineering experts early on in the case to determine causation, reduce risks, and limit costs.
Preeminent Solutions is a WOSB-certified, DBE-certified, MWBE-certified, LDB-certified and soon-to-be 8(a)-certified and civil/structural engineering firm specializing in structural forensics and construction-defect expert witness work.
Contact us for your next aircraft and/or spacecraft hangar construction-defect case.
Long-Span Roof Truss Distress
Hangars house a variety of large-scale aircraft and/or spacecraft vehicles, ranging from hot air balloons to rockets. As a consequence, hangars must employ ample space, broad roofs, and large openings: conditions that are best supported by long-span members.
Long span members include structural elements—such as beams, trusses, or girders — designed to bridge large distances without requiring middle supports or columns.
Hangars typically employ long-span members, arches, cables, portal frames, rigid frames, and/or space frames to create unobstructed aircraft bays.
That said, due to the long spans, such systems are especially sensitive to key issues including:
- Corrosion
- Connection Issues
- Excessive Deflection
- Excessive Vibration Loads
- Excessive Roof Ponding Loads
- Roof Overload (i.e. due to fire suppression systems or other additional weight.)
- Unexpected Suspended Loads (i.e. due to Crane Loading, etc.)
- Transport and Erection During Construction
Key signs of structural overload in long-span steel trusses include:
- Excessive Sagging, particularly at the mid-span
- Loss of Camber (i.e. Loss of Upward Arch)
- Excessive Movement under Lateral Loads
- Twisting of the Top Chord or Bottom
- Out-of-Plank Vertical Members (i.e. Members Lean to or Favor one side).
- Deformed or Folded Flanges
- Global Buckling of Truss
- Cracked Welds
- Sheared-Off or Broken Bolts
- Loosened Nuts
Due to the relatively limited degree of redundancy in long-span systems, smaller issues should be addressed immediately to avoid magnification into larger issues, particularly with connection issues between long-span truss members and the supporting frame members.
Key signs of structural overload in supporting frame members include:
- Excessive Movement under Lateral Loads
- Out-of-Plumb Columns
- Bowing Columns
- Local Web Crippling near Concentrated Lateral Loads
- Local Flange Buckling
- Twisted Girts
- Corroded Base Plates
- Severe Cracking or spalling Near Concrete Plinths/Grout Pads.
- Cracked Welds
Note: Structural overloading is a serious risk to life and public safety. As a consequence, it must be addressed as soon as possible. Contact a qualified structural engineer immediately if your structure displays any of the above signs of overloading.
Consult Preeminent Solutions’ Free Online Education Center for resources and checklists regarding structural overloading issues:
Link: https://psengrinc.com/learning/
Contact a qualified structural engineer if your structure displays any of the above signs of overloading.
Earthquake Load Resistance
Frequently hangar new-builds and/or pre-existing structures are situated in areas with high seismic-risk.
In seismic-prone regions, hangars must maintain structural integrity while protecting aircraft and spacecraft from environmental conditions.
Per the 2024 International Building Code (IBC) Code, the governing code on the matter at time of this publication, in seismic-prone regions, every structure shall be designed and constructed to resist effects of earthquake motions in accordance with ASCE 7.
Key exceptions include:
- Agricultural storage structures not intended for continuous human occupancy
- Wood-framed structures that comply with IBC Section 2308
- Temporary structures in compliance with IBC Section 3013
Earthquakes impart enormous loads unto the vertical force resisting systems and lateral force resisting systems of building structures. As a consequence, poor seismic design and retrofit pose an imminent threat to life and public safety.
Likewise, due to the risk to life, it is best practice to design structures with structural ductility and structural redundancy.
Structural ductility includes a structure’s ability to deform significantly under loads without brittle and/or catastrophic failure. Structural ductility generally includes plastic deformation and redistribution of stress.
Likewise, structural redundancy includes the structure’s ability to provide alternative means of resisting applied loads.
Key signs of low structural ductility include:
- Sudden Catastrophic Failure (i.e. sudden wood beam catastrophic brittle failure.)
- Sudden Snapping Brittle Failure (i.e. sudden concrete or corroded steel snapping failure with little to no observable deformation.)
- Unreinforced or Under-reinforced Masonry
- Unreinforced or Under-reinforced Concrete
- Severely Diagonally Cracked Masonry Members
- Severely Diagonally Cracked Concrete Members
- Severely Corroded Structural Steel with Significant Section Loss
- Weak or Brittle Connections
Similarly, key signs of low structural redundancy include:
- Singular Column Supports with Larger Tributary Areas and Heightened Loads Instead of Multiple Column Supports
- Singular or Fewer Beams with Larger Tributary Areas and Heightened Loads Instead of Multiple / More Beams
- Weak or Brittle Connections
- Lack of Neighboring or Alternative Load
The above issues are especially relevant in the retrofit of older structures.
Consult Preeminent Solutions’ Free Online Education Center for resources and checklists regarding seismic damage:
Link: https://psengrinc.com/learning/
Contact a qualified structural engineer if your structure displays any of the above signs of poor ductility or missing redundancy.
Fire Protection Systems, Water Loads
Hangars encompass exceptionally massive building footprints and are typically comprised of 1 or more Hangar Fire Areas.
Per NFPA 409 guidelines, Hangar Fire Areas include areas within the hangar storage and servicing area, subject to loss by a single fire due to lack of internal subdivisions as specified within the code.
Such large hangar areas require large, distributed fire protection systems to protect life and property.
Per NFPA 409, hangars shall utilize one of the following fire protection strategies within storage and service areas:
- A Prescriptive Approach (i.e. the use the fire protection and life safety systems)
- A Fire-Risk-Based Approach
- A Performance-Based Design Approach
Often designers and builders utilize a prescriptive approach in the design of new hangars and/or retrofit of existing hangars.
Hangar Fire Protection Systems may include large pipe mains, foam systems, deluge piping, tanks, pumps, and suspended
pipe networks. Depending on the configuration, such Fire Protection Systems can impart significant loads unto the hangar roof system.
Key loads from Fire Protection Systems unto hangar vertical and lateral structures include:
- Piping Weight (Dry Lines)
- Piping Weight with Water Loads (Wet Lines Only)
- Sway Bracing Loads (i.e. Loads Under Seismic, Wind, or Other lateral Loads)
- Thrust and Reaction Forces, namely at Pipe Bends, Tees, and End-of-Line Sections
Due to the abundance of long-span elements and limited redundancies, excess loads from fire suppression systems can negatively impact hangar structural elements, namely the roof.
Key structural warning signs of hangar roof overload due to Fire Protection System loading include:
- Sagging or Bowing in Roof Trusses
- Sagging of Rafter Beams
- Sagging Roof Decks at Perimeter
- Loose or Buckling Cross-Bracing
- Cracked Welds
- Sheared Connection Bolts
- Torn or Elongated Gusset Plates
Likewise, depending on the configuration, Fire Protection Systems can impart significant loads unto the hangar column system.
Key structural warning signs of hangar column overload due to fire suppression equipment loading include:
- Slippage or Shear deformation in Bolted Rafter-to-Column
- Out-of-Plumb Columns (Extreme Cases)
- Column Base Plate Uplift or Deformation
- Column Pedestal Cracking (Extreme Cases)
- Cracked Welds
- Sheared Connection Bolts
- Torn or Elongated Gusset Plates
The above issues are especially relevant in the retrofit of older structures.
Consult Preeminent Solutions’ Free Online Education Center for resources and checklists regarding roof overloading issues:
Link: https://psengrinc.com/learning/
Contact a qualified mechanical engineer and/or fire suppression specialist if your structure displays any issues with the fire suppression system.
Contact a qualified structural engineer if your structure displays any of the above signs of structural overloading or other structural issues.
Tornado Missile Resistance
Regularly hangar new-builds and/or pre-existing structures are situated in areas with high tornado missile-risk, due to Hurricanes, Tornados, and/or similar windstorms.
In high tornado missile-risk regions, hangars must maintain structural integrity while protecting aircraft and spacecraft from environmental conditions.
Per the 2024 International Building Code (IBC) Code, the governing code on the matter at time of this publication, the design and construction of Risk Category III and IV buildings and other structures located in tornado-prone regions structures shall be done in accordance with ASCE 7.
Due to the threat to life and public safety it is imperative that structures are able to withstand design tornado-missile load demands, particularly in tornado-prone regions.
Key signs of high tornado missile-risk susceptibility (i.e. poor tornado missile-risk resistance) in buildings include:
- Lack of Structural Redundancy
- Unreinforced or Under-reinforced Masonry Walls
- Unreinforced or Under-reinforced Brick Veneer
- Insufficient Stud Spacing
- Missing or Under-designed Hurricane Strap Connections
- Discontinuous Vertical and Horizontal Load Paths
- Loose and/or Degraded Roof Decking
- Loose and/or Degraded Exterior Wall Panels
- Corroded/Deteriorated Connection Fasteners
- Corroded/Deteriorated Anchorage to Foundation
- Bowing and/or Leaning Columns and Walls (particularly at corners of structure.)
Tornado missiles provide a threat to life and safety and property. As a consequence, it is generally advised to maintain a base level of structural redundancy to accommodate for unintended tornado-missile loads.
Note: Structural redundancy includes the structure’s ability to provide alternative means of resisting applied loads.
Key signs of low structural redundancy include:
- Singular Column Supports with Larger Tributary Areas and Heightened Loads Instead of Multiple Column Supports
- Singular or Fewer Beams with Larger Tributary Areas and Heightened Loads Instead of Multiple / More Beams
- Weak or Brittle Connections
- Lack of Neighboring or Alternative Load Paths.
Key signs of tornado-missile damage in buildings include:
- Concrete Chipping and/or Spalling
- Concrete or Masonry Shear Breakout Cones
- Isolated and/or Localized Steel Column or Joist Dents
- Punctured and/or Deteriorated Girts and Purlins
- Shattered Interior Partition Walls
Consult Preeminent Solutions’ Free Online Education Center for resources and checklists regarding structural performance:
Link: https://psengrinc.com/learning/
Contact a qualified structural engineer if your structure displays any of the above signs of tornado-missile damage.
Slab Capacity for Aircraft/Spacecraft Loads
Hangars protect and support large aircraft and spacecraft vehicles that routinely apply tremendous, concentrated loads unto the foundation slabs.
For example, the typical Airbus A380 commercial Dreamliner vehicle applies over 50,000 lbs of concentrated load per each of its 20 main wheels while taxiing.
Hangar slabs must be designed to withstand such high and concentrated loads repeatedly without failure.
Key signs of concrete failure in foundation slabs include:
- Diagonal/Shear Cracking at Slab Corners
- Severe Cracks That Run Parallel to Slab Control Joints
- Slab Heaving
- Sloping Floors
- Visible slab sinking
- Severe Concrete Cracking
- Concrete Spalling
- Concrete Delamination
Hangar slabs must be properly reinforced to withstand repeated loading over time without failure.
Key signs of concrete under-reinforcement in foundation slabs include:
- Severe Tension Cracking Exceed 1/8 inch
- Severe Map Cracking
- Diagonal/Shear Cracking at Slab Corners
- Widening Crack Growth Over Time with Cyclic Loading
- Slab Heaving
- Sloping Floors
- Visible slab sinking
- Severe Concrete Cracking
- Concrete Spalling
- Concrete Delamination
Consult Preeminent Solutions’ Free Online Education Center for resources and checklists regarding structural capacity issues:
Link: https://psengrinc.com/learning/
Contact a qualified structural engineer if your structure displays any of the above signs of slab or foundation capacity issues.
Preeminent Solutions is a DBE-certified, MWBE-certified, LDB-certified and soon to be 8(a)-certified and WOSB-certified, civil/structural engineering firm.
We have over 30 years’ experience in civil/structural design, forensics, and expert work
We’re Licensed in CA, FL, TX, NJ, NY, DC, MD, VA, TN, MS, GA, NC, SC, LA, & more.
Reach out if your team is in need of structural engineering support.
Preeminent Solutions, Inc.
Forensic Structural Engineers & Consultants
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